Which of the following devices use lasers?
a. DVD players
b. fiber optics communication systems
c. photocopiers
d. UPC price scanners
a, b, d
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Approximately how many states in the range from 5.0 eV to 5.2 eV are there in a copper bar of volume 5.3 cm3?
(h = 6.626 × 10-34 J ? s, h = 1.055 × 10-34 J ? s, mel = 9.11 × 10-31 kg, 1 eV = 1.60 × 10-19 J) A) 1.6 × 1022 B) 5.1 × 1022 C) 3.2 × 1022 D) 8.2 × 1021 E) 3.2 × 1021
Elements heavier than Iron (like Gold) are formed:
A: during Type Ia supernova explosions B: during Type II supernova explosions C: during the deaths of massive stars D: both A and C E: both B and C
The following statements are all true. Which one counts as an "exception to the rule" in being unusual for our solar system?
A) Venus does not have a moon. B) Jupiter has a very small axis tilt. C) Saturn has no solid surface. D) The diameter of Earth's Moon is about 1/4 that of Earth.
Most galaxies in the Local Group are
A) dwarf spirals. B) small irregulars similar to the Magellanic Clouds. C) larger spirals than either the Milky Way or M-31 in Andromeda. D) dwarf ellipticals, similar to the companions of M-31. E) brown dwarfs, with even more dust than our own Galaxy.